Field of the Invention
Embodiments of the invention relate to a solar cell and a method for manufacturing the same.
Description of the Related Art
Recently, as existing energy sources such as petroleum and coal are expected to be depleted, interests in alternative energy sources for replacing the existing energy sources are increasing. Among the alternative energy sources, solar cells generating electric energy from solar energy have been particularly spotlighted.
A silicon solar cell generally includes a substrate and an emitter layer, each of which is formed of a semiconductor, and a plurality of electrodes respectively formed on the substrate and the emitter layer. The semiconductors forming the substrate and the emitter layer have different conductive types, such as a p-type and an n-type. A p-n junction is formed at an interface between the substrate and the emitter layer.
When light is incident on the solar cell, a plurality of electron-hole pairs are generated in the semiconductors. The electron-hole pairs are separated into electrons and holes by the photovoltaic effect. Thus, the separated electrons move to the n-type semiconductor (e.g., the emitter layer) and the separated holes move to the p-type semiconductor (e.g., the substrate). The electrons and holes are respectively collected by the electrodes electrically connected to the emitter layer and the electrodes electrically connected to the substrate. The electrodes are connected to one another using electric wires to thereby obtain electric power.
However, in the solar cell, because the electrodes are formed on the emitter layer on an incident surface of the substrate, on which light is incident, as well as a non-incident surface of the substrate, on which light is not incident, an incident area of light decreases. Hence, efficiency of the solar cell is reduced.
Accordingly, a back contact solar cell, in which all of electrodes collecting electrons and holes are formed on a back surface of a substrate, was developed so as to increase the incident area of light.